package com.codeforces.contest.c299;

import java.util.Scanner;

public class _299B {

	static Scanner scanner = new Scanner(System.in);
	static int n, k;
	static String str;

	public static void main(String[] args) {
		n = scanner.nextInt();
		k = scanner.nextInt();
		str = scanner.next();
		if (str.charAt(0) == '#') {
			System.out.println("NO");
			return;
		}
		int consec = 0;
		for (int i=0;i<n;++i) {
			if (str.charAt(i) == '#') {
				consec++;
				if (consec >= k) {
					System.out.println("NO");
					return;
				}
			}
			else {
				consec = 0;
			}
		}
		System.out.println("YES");
	}

}
